This invention relates to a device and method for inspecting pipes.
Pipes used for example-in heaters and heat exchangers tend to have many bends, many of which are tight U-turns. It is desirable to be able to inspect deeply into the pipes, using a video camera, but the bends make it hard to get the video camera far into the pipe. The first straight section can usually be inspected, and also the second straight section, but it is difficult to inspect the third straight section.
Pipe inspection devices are known which have a video camera head at the end of a cable. A wire helical coil (spring or snake) is disposed between a stop on the cable and the video camera head. The cable may pass through the wire helical coil. When such a device is used to inspect a pipe with bends in it, the wire helical coil can be easily pushed around the first bend and the video camera used to inspect the second straight section. However, as the video camera head passes into the second bend, binding at the first bend and first straight section due to friction of the cable as it winds through the first bend prevents the video camera head from being pushed around the second bend.
It is an object of this invention to provide a pipe inspection device and method for inspecting past the second bend in a pipe having many bends.
There is therefore providing in accordance with an aspect of the invention, a method of inspecting a pipe having a first, second and third straight sections and first and second bends, the method comprising the steps of:
pushing a video camera through the pipe on a cable, with a wire helical coil disposed between the video camera and a stop on the cable, the wire helical coil being long enough to permit passage of the video camera around the first bend;
as the video camera is pushed into the pipe and moves around the first bend, placing a cable stiffener on the cable to stiffen the cable in the first straight section while permitting the cable to move through the cable stiffener; and
pushing the video camera down the second straight section and around the second bend to view the third straight section.
In a further aspect of the invention, there is provided a pipe inspection device, comprising a video camera head, a cable having a stop, a wire helical coil between the video camera head and the stop and a cable stiffener lining the cable on the other side of the stop from the wire helical coil.
In a further aspect of the invention, there is provided a cable stiffener, comprising:
a rod having first and second ends;
a straight slot running along the rod from the first end to the second end for receiving a cable; and
the rod having an enlarged portion along part of the rod forming a centralizer.
Preferably, multiple cable stiffeners are placed on the cable and each cable stiffener is placed on the cable such that the straight slots of adjacent cable stiffeners are rotationally offset from one another. The cable stiffener preferably has a centralizer at one end and the cable stiffener is urged into the pipe with the centralizer forward.
In a further aspect of the invention, the first and second ends of the cable stiffeners are configured for mating with respective second and first ends of adjacent cable stiffeners, and are preferably threaded.
In a further aspect of the invention, the enlarged portion is disposed at one of the ends of the rod, and is tapered towards the second end of the rod.
These and other aspects of the invention are described in the detailed description of the invention and claimed in the claims that follow.